A liquid crystal display device of a TN (Twisted Nematic) type being widely used has high contrast but, on the other hand, has a problem of high visual angle dependence since the molecular axis of the liquid crystal rises due to the vertical electric field. Since demand for a large-sized monitor of a TV or the like is increasing in recent years, a so-called lateral-electric-field-type liquid crystal panel such as the IPS (In-Plane Switching) type or FFS type is being spread, in which an electric field substantially parallel to a substrate for which thin film transistors (hereinafter, called TFTs) are provided is applied to liquid crystal molecules to drive the molecules. A lateral-electric-field-type liquid crystal display panel of, for example, the IPS type has a plurality of pixel electrodes substantially parallel to data line or scan lines on a substrate, and a common electrode which is paired with the pixel electrode. By an electric field substantially parallel to the substrate formed between the pixel electrodes and the common electrode, the liquid crystal molecules are turned in a plane parallel to the substrate, thereby controlling display. By driving the liquid crystal molecules in this manner, the visual angle dependency with respect to the rise angle of the molecular axis is eliminated. The visual angle characteristic is more advantageous as compared with that of the TN type.
Although the IPS type has the visual angle characteristic which is more advantageous than that of the TN type as described above, it has a following problem. Since pixel electrodes and a common electrode are disposed in a comb shape and a lateral electric field is applied, the ratio of the electrode area in a display region is high, and it is difficult to obtain high aperture ratio. To address the problem, there is a technique disclosed in patent literature 1 as means to increase the aperture ratio. FIG. 16 illustrates a pixel structure disclosed in the patent literature 1. In the conventional pixel illustrated in FIG. 16, pixel electrodes and a common electrode extend in a comb-teeth shape in the extension direction of a data line, a second part for coupling the pixel electrodes is formed, and a common signal line overlaps the second part to form storage capacitance by the part, thereby obtaining high aperture ratio.
Another way to increase the aperture ratio may be to reduce a black matrix. For example, in the invention disclosed in patent literature 2, a light shield electrode provided along a signal line is provided below the signal line, and the region between the signal line and the light shield electrode is covered with a black matrix. The width of the black matrix exerting direct influence on the aperture ratio depends on the interval between the light shield electrode and the signal line. Consequently, the interval between the light shield electrode and the signal line cannot be set to a predetermined interval or less to prevent unpreferable generation of capacitance. There is a problem such that the width of the black matrix is not easily decreased.    Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2011-150021    Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2009-103925